U.S. patent number 10,310,215 [Application Number 14/616,826] was granted by the patent office on 2019-06-04 for lens assembly.
This patent grant is currently assigned to ASIA OPTICAL INTERNATIONAL LTD., SINTAI OPTICAL (SHENZHEN) CO., LTD.. The grantee listed for this patent is Asia Optical International Ltd., Sintai Optical (Shenzhen) Co., Ltd.. Invention is credited to Hsi-Ling Chang.
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United States Patent |
10,310,215 |
Chang |
June 4, 2019 |
Lens assembly
Abstract
A lens assembly includes a fifth lens, a first lens, a second
lens, a third lens and a fourth lens, all of which are arranged in
sequence from an object side to an image side along an optical
axis. The second lens is a biconcave lens. The third lens is a
biconvex lens and made of glass material. The fourth lens includes
a concave surface facing the object side.
Inventors: |
Chang; Hsi-Ling (Taichung,
TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sintai Optical (Shenzhen) Co., Ltd.
Asia Optical International Ltd. |
Shenzhen, Guandong Province
Tortola |
N/A
N/A |
CN
GB |
|
|
Assignee: |
SINTAI OPTICAL (SHENZHEN) CO.,
LTD. (Shenzhen, Guandong Province, CN)
ASIA OPTICAL INTERNATIONAL LTD. (Tortola,
VG)
|
Family
ID: |
53882046 |
Appl.
No.: |
14/616,826 |
Filed: |
February 9, 2015 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
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US 20150241671 A1 |
Aug 27, 2015 |
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Foreign Application Priority Data
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|
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Feb 26, 2014 [TW] |
|
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103106432 A |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B
13/0045 (20130101); G02B 9/60 (20130101); G02B
13/004 (20130101); G02B 13/007 (20130101) |
Current International
Class: |
G02B
3/02 (20060101); G02B 13/18 (20060101); G02B
9/60 (20060101); G02B 13/00 (20060101) |
Field of
Search: |
;359/643-830 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101131464 |
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Feb 2008 |
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CN |
|
2013077500 |
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Apr 2013 |
|
JP |
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WO 2014087855 |
|
Jun 2014 |
|
JP |
|
Primary Examiner: Sahle; Mahidere S
Attorney, Agent or Firm: McClure, Qualey & Rodack,
LLP
Claims
What is claimed is:
1. A lens assembly consisting of: a fifth lens which comprises a
convex surface facing an object side and a concave surface facing
an image side; a stop; a first lens which comprises a convex
surface facing the image side; a second lens which is a biconcave
lens; a third lens which is a biconvex lens and made of glass
material; and a fourth lens which comprises a concave surface
facing the object side; wherein the fifth lens, the stop, the first
lens, the second lens, the third lens and the fourth lens are
arranged in sequence from the object side to the image side along
an optical axis; wherein the fifth lens is closer to the object
side than the first lens, the second lens, the third lens and the
fourth lens; wherein the first lens is disposed between the stop
and the second lens; wherein the lens assembly is a fixed-focus
lens assembly; wherein the lens assembly satisfies:
1.6.ltoreq.F.ltoreq.2.0 wherein F is an f-number of the lens
assembly.
2. The lens assembly as claimed in claim 1, wherein the first lens
further comprises a surface, wherein the surface is an aspheric
surface, or the convex surface of the first lens is an aspheric
surface, or both of the surface and the convex surface of the first
lens are aspheric surfaces.
3. The lens assembly as claimed in claim 1, wherein the second lens
comprises two concave surfaces, at least one of which is an
aspheric surface or both of which are aspheric surfaces.
4. The lens assembly as claimed in claim 1, wherein the third lens
comprises two convex surfaces, at least one of which is an aspheric
surface or both of which are aspheric surfaces.
5. The lens assembly as claimed in claim 1, wherein the fourth lens
further comprises a surface, wherein the surface is an aspheric
surface, or the concave surface of the fourth lens is an aspheric
surface, or both of the surface and the concave surface of the
fourth lens are aspheric surfaces.
6. The lens assembly as claimed in claim 1, wherein the fifth lens
further comprises a surface, wherein the surface is an aspheric
surface, or the concave surface of the fifth lens is an aspheric
surface, or both of the surface and the concave surface of the
fifth lens are aspheric surfaces.
7. The lens assembly as claimed in claim 1, wherein the lens
assembly satisfies: 1.34 mm.ltoreq.f.ltoreq.2.777 mm wherein f is
an effective focal length of the lens assembly.
8. A lens assembly consisting of: a fifth lens which comprises a
convex surface facing an object side and a concave surface facing
an image side; a sixth lens which comprises a convex surface facing
the object side and a convex surface facing the image side; a stop;
a first lens which is a biconvex lens; a second lens which is a
biconcave lens; a third lens which is a biconvex lens and made of
glass material; and a fourth lens which comprises a concave surface
facing the object side and a concave surface facing the image side;
wherein the fifth lens, the sixth lens, the stop, the first lens,
the second lens, the third lens and the fourth lens are arranged in
sequence from the object side to the image side along an optical
axis; wherein the fifth lens is closer to the object side than the
sixth lens, the first lens, the second lens, the third lens and the
fourth lens; wherein the sixth lens is disposed between the fifth
lens and the stop; wherein the first lens is disposed between the
stop and the second lens; wherein the lens assembly satisfies:
1.6.ltoreq.F.ltoreq.2.0 wherein F is an f-number of the lens
assembly.
9. The lens assembly as claimed in claim 8, wherein the fifth lens
comprises two surfaces, at least one of which is an aspheric
surface or both of which are aspheric surfaces.
10. The lens assembly as claimed in claim 8, wherein the sixth lens
further comprises a surface, wherein the surface is an aspheric
surface, or the convex surface of the sixth lens is an aspheric
surface, or both of the surface and the convex surface of the sixth
lens are aspheric surfaces.
11. The lens assembly as claimed in claim 8, wherein the first lens
is made of plastic material.
12. The lens assembly as claimed in claim 8, wherein the second
lens is made of plastic material.
13. The lens assembly as claimed in claim 8, wherein the fourth
lens is made of plastic material.
14. The lens assembly as claimed in claim 8, wherein the fifth lens
is made of plastic material.
15. The lens assembly as claimed in claim 8, wherein the sixth lens
is made of plastic material.
16. The lens assembly as claimed in claim 8, wherein the first
lens, the second lens, the fourth lens, the fifth lens and the
sixth lens are made of plastic material.
17. The lens assembly as claimed in claim 8, wherein the lens
assembly satisfies: 1.34 mm.ltoreq.f.ltoreq.2.777 mm wherein f is
an effective focal length of the lens assembly.
18. A lens assembly consisting of: a fifth lens which comprises a
convex surface facing an object side and a concave surface facing
an image side; a first lens which is a biconvex lens and disposed
between the fifth lens and the second lens; a second lens which is
a biconcave lens; a third lens which is a biconvex lens and made of
glass material; and a fourth lens which comprises a concave surface
facing the object side and a concave surface facing the image side;
wherein a focus shift of the lens assembly is between 0 mm and
0.0033 mm as temperature increases from 20.degree. C. to 50.degree.
C.; wherein the lens assembly satisfies: 120
degrees.ltoreq.FOV.ltoreq.168 degrees wherein FOV is a field of
view of the lens assembly; wherein the lens assembly satisfies:
1.34 mm.ltoreq.f.ltoreq.2.777 mm wherein f is an effective focal
length of the lens assembly; wherein the fifth lens, the first
lens, the second lens, the third lens and the fourth lens are
arranged in sequence from the object side to the image side along
an optical axis wherein the fifth lens is closer to the object side
than the first lens, the second lens, the third lens and the fourth
lens.
19. The lens assembly as claimed in claim 18, further comprising a
stop disposed between the fifth lens and the second lens.
20. The lens assembly as claimed in claim 18, further comprising a
stop disposed between the fifth lens and the first lens.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a lens assembly.
2. Description of the Related Art
In order to solve the problem of thermal performance for a lens
assembly, all of the lenses of the lens assembly are made of glass
material. However, such a lens assembly has problems in that the
production cost cannot be reduced and manufacturing and installing
the lens assembly are not easy.
BRIEF SUMMARY OF THE INVENTION
The invention provides a lens assembly wherein most lenses are made
of plastic material and the rest lenses are made of glass material.
Such a lens assembly has no problem of thermal performance, has
reduced production cost, and is easy to manufacture and install.
Also, the lens assembly of the invention still has a good optical
performance and can meet a requirement of resolution.
The lens assembly in accordance with an exemplary embodiment of the
invention includes a fifth lens, a first lens, a second lens, a
third lens and a fourth lens, all of which are arranged in sequence
from an object side to an image side along an optical axis. The
second lens is a biconcave lens. The third lens is a biconvex lens
and made of glass material. The fourth lens includes a concave
surface facing the object side.
In another exemplary embodiment, the first lens includes two
surfaces, at least one of which is an aspheric surface or both of
which are aspheric surfaces.
In yet another exemplary embodiment, the second lens includes two
concave surfaces, at least one of which is an aspheric surface or
both of which are aspheric surfaces.
In another exemplary embodiment, the third lens includes two convex
surfaces, at least one of which is an aspheric surface or both of
which are aspheric surfaces.
In yet another exemplary embodiment, the fourth lens further
includes a surface, wherein the surface is an aspheric surface, or
the concave surface of the fourth lens is an aspheric surface, or
both of the surface and the concave surface of the fourth lens are
aspheric surfaces.
In another exemplary embodiment, the lens assembly further includes
a stop disposed between the fifth lens and the first lens.
In yet another exemplary embodiment, the fifth lens includes two
surfaces, at least one of which is an aspheric surface or both of
which are aspheric surfaces.
In another exemplary embodiment, the lens assembly further includes
a stop disposed between the fifth lens and the second lens.
In yet another exemplary embodiment, the lens assembly further
includes a sixth lens disposed between the fifth lens and the first
lens.
In another exemplary embodiment, the fifth lens includes two
surfaces, at least one of which is an aspheric surface or both of
which are aspheric surfaces.
In yet another exemplary embodiment, the sixth lens includes two
surfaces, at least one of which is an aspheric surface or both of
which are aspheric surfaces.
In another exemplary embodiment, the first lens is made of plastic
material.
In yet another exemplary embodiment, the second lens is made of
plastic material.
In another exemplary embodiment, the fourth lens is made of plastic
material.
In yet another exemplary embodiment, the fifth lens is made of
plastic material.
In another exemplary embodiment, the sixth lens is made of plastic
material.
In yet another exemplary embodiment, the lens assembly further
includes a stop disposed between the sixth lens and the second
lens.
In another exemplary embodiment, the first lens, the second lens,
the fourth lens, the fifth lens and the sixth lens are made of
plastic material.
The lens assembly in accordance with an another exemplary
embodiment of the invention includes a fifth lens, a first lens, a
second lens, a third lens and a fourth lens, all of which are
arranged in sequence from an object side to an image side along an
optical axis. The first lens is a biconvex lens. The second lens is
a biconcave lens. The third lens is a biconvex lens and made of
glass material. The fourth lens includes a concave surface facing
the object side.
In another exemplary embodiment, the lens assembly further includes
a stop disposed between the fifth lens and the first lens.
A detailed description is given in the following embodiments with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
FIG. 1 is a lens layout and optical path diagram of a lens assembly
in accordance with a first embodiment of the invention;
FIG. 2A depicts a field curvature diagram of the lens assembly in
accordance with the first embodiment of the invention;
FIG. 2B is a distortion diagram of the lens assembly in accordance
with the first embodiment of the invention;
FIG. 2C is a modulation transfer function diagram of the lens
assembly in accordance with the first embodiment of the
invention;
FIG. 2D is a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly in
accordance with the first embodiment of the invention;
FIG. 2E is a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly in
accordance with the first embodiment of the invention;
FIG. 3 is a lens layout and optical path diagram of a lens assembly
in accordance with a second embodiment of the invention;
FIG. 4A depicts a field curvature diagram of the lens assembly in
accordance with the second embodiment of the invention;
FIG. 4B is a distortion diagram of the lens assembly in accordance
with the second embodiment of the invention;
FIG. 4C is a modulation transfer function diagram of the lens
assembly in accordance with the second embodiment of the
invention;
FIG. 4D is a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly in
accordance with the second embodiment of the invention;
FIG. 4E is a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly in
accordance with the second embodiment of the invention;
FIG. 5 is a lens layout and optical path diagram of a lens assembly
in accordance with a third embodiment of the invention;
FIG. 6A depicts a field curvature diagram of the lens assembly in
accordance with the third embodiment of the invention;
FIG. 6B is a distortion diagram of the lens assembly in accordance
with the third embodiment of the invention;
FIG. 6C is a modulation transfer function diagram of the lens
assembly in accordance with the third embodiment of the
invention;
FIG. 6D is a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly in
accordance with the third embodiment of the invention; and
FIG. 6E is a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly in
accordance with the third embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The following description is made for the purpose of illustrating
the general principles of the invention and should not be taken in
a limiting sense. The scope of the invention is best determined by
reference to the appended claims.
Referring to FIG. 1, FIG. 1 is a lens layout and optical path
diagram of a lens assembly in accordance with a first embodiment of
the invention. The lens assembly 1 includes a stop ST1, a first
lens L11, a second lens L12, a third lens L13, a fourth lens L14
and an optical filter OF1, all of which are arranged in sequence
from an object side to an image side along an optical axis OA1. In
operation, an image of light rays from the object side is formed at
an image plane IMA1. The first lens L11 is a biconvex lens and made
of plastic material, wherein both of the object side surface S12
and image side surface S13 are aspheric surfaces. The second lens
L12 is a biconcave lens and made of plastic material, wherein both
of the object side surface S14 and image side surface S15 are
aspheric surfaces. The third lens L13 is a biconvex lens and made
of glass material, wherein both of the object side surface S16 and
image side surface S17 are aspheric surfaces. The fourth lens L14
is made of plastic material, wherein the object side surface S18 is
a concave surface, the image side surface S19 is a concave surface
and both of the object side surface S18 and image side surface S19
are aspheric surfaces. Both of the object side surface S110 and
image side surface S111 of the optical filter OF1 are plane
surfaces.
By the above design of the lenses and stop ST1, the lens assembly 1
can effectively solve the problem of thermal performance, correct
aberration, maintain good optical performance and meet the
requirement of image resolution.
In order to achieve the above purposes and effectively enhance the
optical performance, the lens assembly 1 in accordance with the
first embodiment of the invention is provided with the optical
specifications shown in Table 1, which include the effective focal
length, F-number, field of view, radius of curvature of each lens
surface, thickness between adjacent surface, refractive index of
each lens and Abbe number of each lens. Table 1 shows that the
effective focal length is equal to 4.1 mm, F-number is equal to 1.3
and field of view is equal to 120.degree. for the lens assembly 1
of the first embodiment of the invention.
TABLE-US-00001 TABLE 1 Effective Focal Length = 4.1 mm F-number =
1.3 Field of View = 120.degree. Radius of Surface Curvature
Thickness Number (mm) (mm) Nd Vd Remark S11 .infin. -0.59 Stop ST1
S12 3.36 1.92 1.636 23.89 The First Lens L11 S13 23.48 0.27 S14
20.86 0.59 1.636 23.89 The Second Lens L12 S15 3.51 0.24 S16 8.61
1.81 1.804 40.89 The Third Lens L13 S17 -3.42 0.17 S18 22.64 0.92
1.544 56.09 The Fourth Lens L14 S19 2.49 0.8 S110 .infin. 0.3 1.5
56 Optical Filter OF1 S111 .infin. 0.7
The aspheric surface sag z of each lens in table 1 can be
calculated by the following formula:
z=ch.sup.2/{1+[1-(k+1)c.sup.2h.sup.2].sup.1/2}+Ah.sup.4+Bh.sup.6+Ch.sup.8-
+Dh.sup.10+Eh.sup.12+Fh.sup.14+Gh.sup.16 where c is curvature, h is
the vertical distance from the lens surface to the optical axis, k
is conic constant and A, B, C, D, E, F and G are aspheric
coefficients.
In the first embodiment, the conic constant k and the aspheric
coefficients A, B, C, D, E, F, G of each surface are shown in Table
2.
TABLE-US-00002 TABLE 2 Surface Number k A B C D E F G S12 -0.058804
-0.001909 0.000622 -0.000397 0.000016 0.000007 0.000001 -7.7-
53E-07 S13 100.045238 -0.026439 0.001816 0.000495 -0.000781
0.000284 -0.000045 0.- 000003 S14 -100.002968 -0.070434 0.011034
0.003524 -0.002483 0.000695 -0.000099 0- .000006 S15 1.620541
-0.053290 0.000449 0.004843 -0.003177 0.001121 -0.000211 0.00- 0017
S16 7.415972 0.007139 -0.005719 -0.002215 0.001938 -0.000635
-0.000104 -0.- 000006 S17 -4.636813 0.009301 -0.000492 -0.000067
-0.000109 0.000029 0.000006 -0.- 000001 S18 96.770029 -0.030967
0.004390 -0.000065 -0.000566 0.000200 -0.000022 5.- 4449E-07 S19
-5.052414 -0.028229 0.007202 -0.001125 0.000005 0.000026 -0.000004
1.5- 579E-07
By the above arrangements of the lenses and stop ST1, the lens
assembly 1 of the first embodiment can meet the requirements of
optical performance and thermal performance as seen in FIGS. 2A-2E,
wherein FIG. 2A shows a field curvature of the lens assembly 1 in
accordance with the first embodiment of the invention, FIG. 2B
shows a distortion diagram of the lens assembly 1 in accordance
with the first embodiment of the invention, FIG. 2C shows a
modulation transfer function diagram of the lens assembly 1 in
accordance with the first embodiment of the invention, FIG. 2D
shows a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly 1 in
accordance with the first embodiment of the invention and FIG. 2E
shows a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly 1 in
accordance with the first embodiment of the invention.
It can be seen from FIG. 2A that the field curvature of tangential
direction and sagittal direction in the lens assembly 1 of the
first embodiment ranges between -0.045 mm and 0.050 mm for the
wavelength of 0.850 .mu.m. It can be seen from FIG. 2B that the
distortion in the lens assembly 1 of the first embodiment ranges
between 0.0% and 2.5% for the wavelength of 0.850 .mu.m. It can be
seen from FIG. 2C that the modulation transfer function of
tangential direction and sagittal direction in the lens assembly 1
of the first embodiment ranges between 0.60 and 1.0 wherein the
wavelength is 0.850 .mu.m, each field is 0.0000 mm, 0.6300 mm,
2.5200 mm and 3.1500 mm, spatial frequency ranges between 0 lp/mm
and 45 lp/mm. It can be seen from FIG. 2D that the through focus
modulation transfer function of tangential direction and sagittal
direction in the lens assembly 1 of the first embodiment has
maximum modulation transfer function value as focus shift is equal
to 0 mm wherein the wavelength is 0.850 .mu.m, field is 0.0000 mm,
spatial frequency is equal to 45 lp/mm, and temperature is equal to
20.degree. C. It can be seen from FIG. 2E that the through focus
modulation transfer function of tangential direction and sagittal
direction in the lens assembly 1 of the first embodiment has
maximum modulation transfer function value as focus shift is about
equal to 0.0033 mm wherein the wavelength is 0.850 .mu.m, field is
0.0000 mm, spatial frequency is equal to 45 lp/mm, and temperature
is equal to 50.degree. C. It can be seen from FIG. 2D and FIG. 2E
that the focus shift is about equal to 0.11 .mu.m/.degree. C. in
the lens assembly 1 of the first embodiment as temperature
increases from 20.degree. C. to 50.degree. C. It is obvious that
the field curvature and the distortion of the lens assembly 1 of
the first embodiment can be corrected effectively, the image
resolution and thermal performance can meet the requirements.
Therefore, the lens assembly 1 of the first embodiment is capable
of good optical performance.
Referring to FIG. 3, FIG. 3 is a lens layout and optical path
diagram of a lens assembly in accordance with a second embodiment
of the invention. The lens assembly 2 includes a fifth lens L25, a
stop ST2, a first lens L21, a second lens L22, a third lens L23, a
fourth lens L24 and an optical filter OF2, all of which are
arranged in sequence from an object side to an image side along an
optical axis OA2. In operation, an image of light rays from the
object side is formed at an image plane IMA2. The fifth lens L25 is
a meniscus lens and made of plastic material, wherein the object
side surface S21 is a convex surface, the image side surface S22 is
a concave surface and both of the object side surface S21 and image
side surface S22 are aspheric surfaces. The first lens L21 is a
biconvex lens and made of plastic material, wherein both of the
object side surface S24 and image side surface S25 are aspheric
surfaces. The second lens L22 is a biconcave lens and made of
plastic material, wherein both of the object side surface S26 and
image side surface S27 are aspheric surfaces. The third lens L23 is
a biconvex lens and made of glass material, wherein both of the
object side surface S28 and image side surface S29 are aspheric
surfaces. The fourth lens L24 is made of plastic material, wherein
the object side surface S210 is a concave surface, the image side
surface S211 is a concave surface and both of the object side
surface S210 and image side surface S211 are aspheric surfaces.
Both of the object side surface S212 and image side surface S213 of
the optical filter OF2 are plane surfaces.
By the above design of the lenses and stop ST2, the lens assembly 2
can effectively solve the problem of thermal performance, correct
aberration, maintain good optical performance and meet the
requirement of image resolution.
In order to achieve the above purposes and effectively enhance the
optical performance, the lens assembly 2 in accordance with the
second embodiment of the invention is provided with the optical
specifications shown in Table 3, which include the effective focal
length, F-number, field of view, radius of curvature of each lens
surface, thickness between adjacent surface, refractive index of
each lens and Abbe number of each lens. Table 3 shows that the
effective focal length is equal to 1.34 mm, F-number is equal to
1.6 and field of view is equal to 144.degree. for the lens assembly
2 of the second embodiment of the invention.
TABLE-US-00003 TABLE 3 Effective Focal Length = 1.34 mm F-number =
1.6 Field of View = 144.degree. Radius of Surface Curvature
Thickness Number (mm) (mm) Nd Vd Remark S21 1.219993 0.427714 1.534
56 The Fifth Lens L25 S22 0.536677 1.178114 S23 .infin. -0.187158
Stop ST2 S24 1.083945 0.548184 1.534 56 The First Lens L21 S25
-2.928161 0.1 S26 2.079373 0.246952 1.612 26.29 The Second Lens L22
S27 0.722024 0.087564 S28 1.382242 0.708689 1.592 67.19 The Third
Lens L23 S29 -0.926232 0.053121 S210 3.832610 0.317775 1.612 26.29
The Fourth Lens L24 S211 1.237753 0.207080 S212 .infin. 0.21 1.5 54
Optical Filter OF2 S213 .infin. 0.552128
The aspheric surface sag z of each lens in table 3 can be
calculated by the following formula:
z=ch.sup.2/{1+[1-(k+1)c.sup.2h.sup.2].sup.1/2}+Ah.sup.4+Bh.sup.6+Ch.sup.8-
+Dh.sup.10+Eh.sup.12+Fh.sup.14+Gh.sup.16 where c is curvature, h is
the vertical distance from the lens surface to the optical axis, k
is conic constant and A, B, C, D, E, F and G are aspheric
coefficients.
In the second embodiment, the conic constant k and the aspheric
coefficients A, B, C, D, E, F, G of each surface are shown in Table
4.
TABLE-US-00004 TABLE 4 Surface Number k A B C D E F G S21 -0.694160
-0.097324 0.005794 -0.000640 0 0 0 0 S22 -1.073163 0.217836
0.120490 0.136987 0 0 0 0 S24 -0.064752 -0.018269 0.411204
-0.733814 0 0 0 0 S25 1.339428 -0.174064 1.159769 -2.206076 0 0 0 0
S26 -87.315508 -0.815321 1.772638 -3.122060 0 0 0 0 S27 -7.970520
-0.100325 0.008587 0.304068 0 0 0 0 S28 0 -0.279092 0.530369
-0.239221 0 0 0 S29 0 0.617977 -0.467260 0.887943 0 0 0 0 S210 0
-0.328287 0.007636 -0.194721 -0.069393 0 0 0 S211 -8.347093
-0.247464 0.254505 -0.315575 0.152627 0 0 0
By the above arrangements of the lenses and stop ST2, the lens
assembly 2 of the second embodiment can meet the requirements of
optical performance and thermal performance as seen in FIGS. 4A-4E,
wherein FIG. 4A shows a field curvature of the lens assembly 2 in
accordance with the second embodiment of the invention, FIG. 4B
shows a distortion diagram of the lens assembly 2 in accordance
with the second embodiment of the invention, FIG. 4C shows a
modulation transfer function diagram of the lens assembly 2 in
accordance with the second embodiment of the invention, FIG. 4D
shows a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly 2 in
accordance with the second embodiment of the invention and FIG. 4E
shows a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly 2 in
accordance with the second embodiment of the invention.
It can be seen from FIG. 4A that the field curvature of tangential
direction and sagittal direction in the lens assembly 2 of the
second embodiment ranges between -0.06 mm and 0.12 mm for the
wavelength of 0.400 .mu.m, 0.555 .mu.m and 0.750 .mu.m. It can be
seen from FIG. 4B that the distortion in the lens assembly 2 of the
second embodiment ranges between -1.4% and 0.0% for the wavelength
of 0.400 .mu.m, 0.555 .mu.m and 0.750 .mu.m. It can be seen from
FIG. 4C that the modulation transfer function of tangential
direction and sagittal direction in the lens assembly 2 of the
second embodiment ranges between 0.28 and 1.0 wherein the
wavelength ranges between 0.400 .mu.m and 0.750 .mu.m, each field
is 0.0000 mm, 0.1200 mm, 0.8400 mm and 1.2000 mm, spatial frequency
ranges between 0 lp/mm and 160 lp/mm. It can be seen from FIG. 4D
that the through focus modulation transfer function of tangential
direction and sagittal direction in the lens assembly 2 of the
second embodiment has maximum modulation transfer function value as
focus shift is equal to 0 mm wherein the wavelength ranges between
0.400 .mu.m and 0.750 .mu.m, field is 0.0000 mm, spatial frequency
is equal to 80 lp/mm, and temperature is equal to 20.degree. C. It
can be seen from FIG. 4E that the through focus modulation transfer
function of tangential direction and sagittal direction in the lens
assembly 2 of the second embodiment has maximum modulation transfer
function value as focus shift is about equal to 0.003 mm wherein
the wavelength ranges between 0.400 .mu.m and 0.750 .mu.m, field is
0.0000 mm, spatial frequency is equal to 80 lp/mm, and temperature
is equal to 50.degree. C. It can be seen from FIG. 4D and FIG. 4E
that the focus shift is about equal to 0.1 .mu.m/.degree. C. in the
lens assembly 2 of the second embodiment as temperature increases
from 20.degree. C. to 50.degree. C. It is obvious that the field
curvature and the distortion of the lens assembly 2 of the second
embodiment can be corrected effectively, the image resolution and
thermal performance can meet the requirements. Therefore, the lens
assembly 2 of the second embodiment is capable of good optical
performance.
Referring to FIG. 5, FIG. 5 is a lens layout and optical path
diagram of a lens assembly in accordance with a third embodiment of
the invention. The lens assembly 3 includes a fifth lens L35, a
sixth lens L36, a stop ST3, a first lens L31, a second lens L32, a
third lens L33, a fourth lens L34 and an optical filter OF3, all of
which are arranged in sequence from an object side to an image side
along an optical axis OA3. In operation, an image of light rays
from the object side is formed at an image plane IMA3. The fifth
lens L35 is a meniscus lens and made of plastic material, wherein
the object side surface S31 is a convex surface, the image side
surface S32 is a concave surface and both of the object side
surface S31 and image side surface S32 are aspheric surfaces. The
sixth lens L36 is made of plastic material, wherein the object side
surface S33 is a convex surface, the image side surface S34 is a
convex surface (look like a plane surface) and both of the object
side surface S33 and image side surface S34 are aspheric surfaces.
The first lens L31 is a biconvex lens and made of plastic material,
wherein both of the object side surface S36 and image side surface
S37 are aspheric surfaces. The second lens L32 is a biconcave lens
and made of plastic material, wherein both of the object side
surface S38 and image side surface S39 are aspheric surfaces. The
third lens L33 is a biconvex lens and made of glass material,
wherein both of the object side surface S310 and image side surface
S311 are spherical surfaces. The fourth lens L34 is made of plastic
material, wherein the object side surface S312 is a concave
surface, the image side surface S313 is a concave surface (look
like a plane surface) and both of the object side surface S312 and
image side surface S313 are aspheric surfaces. Both of the object
side surface S314 and image side surface S315 of the optical filter
OF3 are plane surfaces.
By the above design of the lenses and stop ST3, the lens assembly 3
can effectively solve the problem of thermal performance, correct
aberration, maintain good optical performance and meet the
requirement of image resolution.
In order to achieve the above purposes and effectively enhance the
optical performance, the lens assembly 3 in accordance with the
third embodiment of the invention is provided with the optical
specifications shown in Table 5, which include the effective focal
length, F-number, field of view, radius of curvature of each lens
surface, thickness between adjacent surface, refractive index of
each lens and Abbe number of each lens. Table 3 shows that the
effective focal length is equal to 2.777 mm, F-number is equal to
2.0 and field of view is equal to 168.degree. for the lens assembly
3 of the third embodiment of the invention.
TABLE-US-00005 TABLE 5 Effective Focal Length = 2.777 mm F-number =
2.0 Field of View = 168.degree. Radius of Surface Curvature
Thickness Number (mm) (mm) Nd Vd Remark S31 13.070438 1.398 1.534
56.07 The Fifth Lens L35 S32 2.193243 3.036 S33 16.812734 7.589
1.614 25.57 The Sixth Lens L36 S34 -56.910637 0.168 S35 .infin.
0.435 Stop ST3 S36 4.628216 1.576 1.534 56.07 The First Lens L31
S37 -4.677102 0.648 S38 -7.706641 0.574 1.614 25.57 The Second Lens
L32 S39 5.936748 0.106 S310 5.769723 2.016 1.693 53.20 The Third
Lens L33 S311 -5.769723 0.648 S312 -9.088463 1.258 1.614 25.57 The
Fourth Lens L34 S313 96.310159 1.162 S314 .infin. 0.4 1.5 54
Optical Filter OF3 S315 .infin. 1
The aspheric surface sag z of each lens in table 5 can be
calculated by the following formula:
z=ch.sup.2/{1+[1-(k+1)c.sup.2h.sup.2].sup.1/2}+Ah.sup.4+Bh.sup.6+Ch.sup.8-
+Dh.sup.10+Eh.sup.12+Fh.sup.14+Gh.sup.16 where c is curvature, h is
the vertical distance from the lens surface to the optical axis, k
is conic constant and A, B, C, D, E, F and G are aspheric
coefficients.
In the third embodiment, the conic constant k and the aspheric
coefficients A, B, C, D, E, F, G of each surface are shown in Table
6.
TABLE-US-00006 TABLE 6 Surface Number k A B C D E F G S31 -2.274595
-0.000115 -0.000002 9.4621E-08 0 0 0 0 S32 -0.940345 0.002074
0.000093 0.000003 0 0 0 0 S33 -9.283708 -0.001434 0.000065
-0.000007 0 0 0 0 S34 -134.824538 -0.002515 0.000833 -0.000004 0 0
0 0 S36 -3.147746 -0.002869 0.000678 -0.000027 0 0 0 0 S37
-0.073438 -0.000805 0.000293 -0.000028 0 0 0 0 S38 -24.522163
-0.002088 0.000315 -0.000145 0 0 0 0 S39 -0.112862 0.005741
-0.000860 0.000024 0 0 0 0 S312 45.446473 -0.010697 0.000315
0.000034 0 0 0 0 S313 1421.828203 -0.003067 0.000101 0.000041 0 0 0
0
By the above arrangements of the lenses and stop ST3, the lens
assembly 3 of the third embodiment can meet the requirements of
optical performance and thermal performance as seen in FIGS. 6A-6E,
wherein FIG. 6A shows a field curvature of the lens assembly 3 in
accordance with the third embodiment of the invention, FIG. 6B
shows a distortion diagram of the lens assembly 3 in accordance
with the third embodiment of the invention, FIG. 6C shows a
modulation transfer function diagram of the lens assembly 3 in
accordance with the third embodiment of the invention, FIG. 6D
shows a through focus modulation transfer function diagram as
temperature is equal to 20.degree. C. for the lens assembly 3 in
accordance with the third embodiment of the invention and FIG. 6E
shows a through focus modulation transfer function diagram as
temperature is equal to 50.degree. C. for the lens assembly 3 in
accordance with the third embodiment of the invention.
It can be seen from FIG. 6A that the field curvature of tangential
direction and sagittal direction in the lens assembly 3 of the
third embodiment ranges between -0.040 mm and 0.015 mm for the
wavelength of 0.460 .mu.m, 0.540 .mu.m and 0.605 .mu.m. It can be
seen from FIG. 6B that the distortion in the lens assembly 3 of the
third embodiment ranges between -0.2% and 1.4% for the wavelength
of 0.460 .mu.m, 0.540 .mu.m and 0.605 .mu.m. It can be seen from
FIG. 6C that the modulation transfer function of tangential
direction and sagittal direction in the lens assembly 3 of the
third embodiment ranges between 0.21 and 1.0 wherein the wavelength
ranges between 0.460 .mu.m and 0.605 .mu.m, each field is 0.0000
mm, 0.3046 mm, 1.8276 mm and 3.0460 mm, spatial frequency ranges
between 0 lp/mm and 220 lp/mm. It can be seen from FIG. 6D that the
through focus modulation transfer function of tangential direction
and sagittal direction in the lens assembly 3 of the third
embodiment has maximum modulation transfer function value as focus
shift is equal to 0 mm wherein the wavelength ranges between 0.460
.mu.m and 0.605 .mu.m, field is 0.0000 mm, spatial frequency is
equal to 75 lp/mm, and temperature is equal to 20.degree. C. It can
be seen from FIG. 6E that the through focus modulation transfer
function of tangential direction and sagittal direction in the lens
assembly 3 of the third embodiment has maximum modulation transfer
function value as focus shift is about equal to 0.0033 mm wherein
the wavelength ranges between 0.460 .mu.m and 0.605 .mu.m, field is
0.0000 mm, spatial frequency is equal to 75 lp/mm, and temperature
is equal to 50.degree. C. It can be seen from FIG. 6D and FIG. 6E
that the focus shift is about equal to 0.11 .mu.m/.degree. C. in
the lens assembly 3 of the third embodiment as temperature
increases from 20.degree. C. to 50.degree. C. It is obvious that
the field curvature and the distortion of the lens assembly 3 of
the third embodiment can be corrected effectively, the image
resolution and thermal performance can meet the requirements.
Therefore, the lens assembly 3 of the third embodiment is capable
of good optical performance.
In the above first embodiment, both of the object side surface and
image side surface of the first, second, third and fourth lens are
aspheric surfaces. However, it has the same effect and falls into
the scope of the invention that any of the object side surfaces or
image side surfaces of the first, second, third and fourth lens are
changed into spherical surfaces.
In the above second embodiment, both of the object side surface and
image side surface of the fifth, first, second, third and fourth
lens are aspheric surfaces. However, it has the same effect and
falls into the scope of the invention that any of the object side
surfaces or image side surfaces of the fifth, first, second, third
and fourth lens are changed into spherical surfaces.
In the above second embodiment, the stop ST2 is disposed between
the fifth lens L25 and the first lens L21. However, it has the same
effect and falls into the scope of the invention that the stop ST2
is disposed between the first lens L21 and the second lens L22.
In the above third embodiment, both of the object side surface and
image side surface of the sixth, fifth, first, second and fourth
lens are aspheric surfaces, both of the object side surface and
image side surface of the third lens are spherical surfaces.
However, it has the same effect and falls into the scope of the
invention that any of the object side surfaces or image side
surfaces of the sixth, fifth, first, second and fourth lens are
changed into spherical surfaces and/or at least one of the object
side surface or image side surface of the first lens is changed
into aspheric surface.
In the above third embodiment, the stop ST3 is disposed between the
sixth lens L36 and the first lens L31. However, it has the same
effect and falls into the scope of the invention that the stop ST3
is disposed between the first lens L31 and the second lens L32.
* * * * *